class Maybe {
  static of(value) {
    return new Maybe(value);
  }

  constructor(value) {
    this._value = value;
  }

  map(fn) {
    return this.isNothing(this._value)
      ? Maybe.of(this._value)
      : Maybe.of(fn(this._value));
  }

  isNothing(value) {
    return value === null || value === undefined;
  }
}

class Container {
  static of(value) {
    return new Container(value);
  }

  constructor(value) {
    this._value = value;
  }

  map(fn) {
    return new Container(fn(this._value));
  }
}

module.exports = { Maybe, Container };
